diff --git a/internal/runtime/executor/devin_executor.go b/internal/runtime/executor/devin_executor.go
index 7f39d3643..8a1fe4785 100644
--- a/internal/runtime/executor/devin_executor.go
+++ b/internal/runtime/executor/devin_executor.go
@@ -594,9 +594,12 @@ func (e *DevinExecutor) streamDevinFrames(
 	var lastStopReason uint64
 	sawEOS := false
 
-	// Buffer subsequent content/tools while thinking is active so late-arriving or split
-	// thought signatures can be emitted before closing the thinking content block.
+	// Keep tools and block-oriented content queued for late or split thought signatures.
+	// OpenAI text can stream independently, but must not overtake queued tools.
+	streamContentEarly := responseFormat == sdktranslator.FormatOpenAI || responseFormat == sdktranslator.FormatOpenAIResponse
 	var pendingActions []func() bool
+	var deferredThoughtStops []int
+	responseThoughtSignatures := make(map[int]string)
 
 	flushPendingActions := func() bool {
 		if thoughtStarted {
@@ -629,9 +632,15 @@ func (e *DevinExecutor) streamDevinFrames(
 			if stopIdx < 0 {
 				stopIdx = stepIndex
 			}
-			stopEvent, _ := sjson.SetBytes([]byte(`{"event_type":"step.stop","index":0}`), "index", stopIdx)
-			if !emitInteractionsEvent(stopEvent) {
-				return false
+			if responseFormat == sdktranslator.FormatOpenAIResponse {
+				// Responses items may overlap. Keep reasoning open for late signatures
+				// so output_item.done and response.completed contain the same item.
+				deferredThoughtStops = append(deferredThoughtStops, stopIdx)
+			} else {
+				stopEvent, _ := sjson.SetBytes([]byte(`{"event_type":"step.stop","index":0}`), "index", stopIdx)
+				if !emitInteractionsEvent(stopEvent) {
+					return false
+				}
 			}
 			thoughtStarted = false
 			stepIndex++
@@ -744,6 +753,11 @@ func (e *DevinExecutor) streamDevinFrames(
 	}
 
 	closeOpenSteps := func() {
+		for _, index := range deferredThoughtStops {
+			stopEvent, _ := sjson.SetBytes([]byte(`{"event_type":"step.stop","index":0}`), "index", index)
+			_ = emitInteractionsEvent(stopEvent)
+		}
+		deferredThoughtStops = nil
 		if len(pendingActions) > 0 || thoughtStarted {
 			_ = flushPendingActions()
 		}
@@ -940,7 +954,13 @@ func (e *DevinExecutor) streamDevinFrames(
 			}
 			sigEvent := []byte(`{"event_type":"step.delta","index":0,"delta":{"type":"thought_signature","signature":""}}`)
 			sigEvent, _ = sjson.SetBytes(sigEvent, "index", targetIdx)
-			sigEvent, _ = sjson.SetBytes(sigEvent, "delta.signature", string(frameRes.DeltaSignature))
+			sig := string(frameRes.DeltaSignature)
+			if responseFormat == sdktranslator.FormatOpenAIResponse {
+				// The Responses translator accepts complete signatures, not fragments.
+				responseThoughtSignatures[targetIdx] += sig
+				sig = responseThoughtSignatures[targetIdx]
+			}
+			sigEvent, _ = sjson.SetBytes(sigEvent, "delta.signature", sig)
 			if frameRes.DeltaSignatureType != "" {
 				sigEvent, _ = sjson.SetBytes(sigEvent, "delta.signature_type", frameRes.DeltaSignatureType)
 			}
@@ -968,7 +988,7 @@ func (e *DevinExecutor) streamDevinFrames(
 			accumulatedContent.WriteString(frameRes.ContentText)
 			chunk := contentBuf.Feed([]byte(frameRes.ContentText))
 			if chunk != "" {
-				if thoughtStarted {
+				if thoughtStarted && (!streamContentEarly || len(pendingActions) > 0) {
 					capturedChunk := chunk
 					pendingActions = append(pendingActions, func() bool {
 						return emitContentChunk(capturedChunk)
diff --git a/internal/runtime/executor/devin_executor_test.go b/internal/runtime/executor/devin_executor_test.go
index ec849d1ac..f3b781538 100644
--- a/internal/runtime/executor/devin_executor_test.go
+++ b/internal/runtime/executor/devin_executor_test.go
@@ -3800,7 +3800,8 @@ func TestDevinExecutor_WarnsWhenUpstreamServesUnexpectedModel(t *testing.T) {
 
 	exec := NewDevinExecutor(&config.Config{})
 	auth := &cliproxyauth.Auth{
-		ID:         "devin-auth-unexpected",
+		// Isolate this run from the process-wide model warning throttle.
+		ID:         "devin-auth-unexpected-" + uuid.NewString(),
 		Provider:   "devin",
 		Attributes: map[string]string{"api_key": "test-key"},
 	}
diff --git a/internal/runtime/executor/devin_stream_content_test.go b/internal/runtime/executor/devin_stream_content_test.go
new file mode 100644
index 000000000..0e8c674bd
--- /dev/null
+++ b/internal/runtime/executor/devin_stream_content_test.go
@@ -0,0 +1,326 @@
+package executor
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"io"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/router-for-me/CLIProxyAPI/v8/internal/runtime/executor/helps"
+	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v8/sdk/cliproxy/executor"
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v8/sdk/translator"
+	"github.com/tidwall/gjson"
+	"google.golang.org/protobuf/encoding/protowire"
+)
+
+type devinContentCheckpointReader func([]byte) (int, error)
+
+func (r devinContentCheckpointReader) Read(p []byte) (int, error) {
+	return r(p)
+}
+
+func TestDevinStreamEmitsContentBeforeThinkingCloses(t *testing.T) {
+	for _, format := range []sdktranslator.Format{sdktranslator.FormatOpenAI, sdktranslator.FormatOpenAIResponse} {
+		t.Run(string(format), func(t *testing.T) {
+			// Each checkpoint runs synchronously when the executor requests the next
+			// frame, after all output for the previous frame has been enqueued.
+			// EOS is unavailable until every pre-EOS assertion has run.
+			out := make(chan cliproxyexecutor.StreamChunk, 64)
+			var content []string
+			var thinking strings.Builder
+			drain := func() {
+				for len(out) > 0 {
+					chunk := <-out
+					if chunk.Err != nil {
+						t.Fatalf("unexpected stream error: %v", chunk.Err)
+					}
+					for _, line := range strings.Split(string(chunk.Payload), "\n") {
+						data := strings.TrimSpace(strings.TrimPrefix(line, "data: "))
+						if !gjson.Valid(data) {
+							continue
+						}
+						event := gjson.Parse(data)
+						var text string
+						switch format {
+						case sdktranslator.FormatOpenAI:
+							thinking.WriteString(event.Get("choices.0.delta.reasoning_content").String())
+							text = event.Get("choices.0.delta.content").String()
+						case sdktranslator.FormatOpenAIResponse:
+							switch event.Get("type").String() {
+							case "response.reasoning_summary_text.delta":
+								thinking.WriteString(event.Get("delta").String())
+							case "response.output_text.delta":
+								text = event.Get("delta").String()
+							}
+						}
+						if text != "" {
+							content = append(content, text)
+						}
+					}
+				}
+			}
+
+			stages := []struct {
+				name  string
+				field protowire.Number
+				text  string
+				want  []string
+			}{
+				{name: "thinking", field: 9, text: "planning"},
+				{name: "incomplete UTF-8", field: 3, text: "甲"[:1]},
+				{name: "first complete UTF-8 chunk", field: 3, text: "甲"[1:], want: []string{"甲"}},
+				{name: "second complete UTF-8 chunk", field: 3, text: "乙", want: []string{"甲", "乙"}},
+			}
+			var readers []io.Reader
+			checkpoints := 0
+			for _, stage := range stages {
+				frame := protowire.AppendTag(nil, stage.field, protowire.BytesType)
+				frame = protowire.AppendString(frame, stage.text)
+				readers = append(readers, bytes.NewReader(helps.WrapConnectEnvelope(frame)))
+				readers = append(readers, devinContentCheckpointReader(func(_ []byte) (int, error) {
+					drain()
+					checkpoints++
+					if thinking.String() != "planning" {
+						t.Fatalf("%s: thinking = %q, want planning before EOS", stage.name, thinking.String())
+					}
+					if !slices.Equal(content, stage.want) {
+						t.Errorf("%s: content deltas before upstream EOS = %q, want %q", stage.name, content, stage.want)
+					}
+					return 0, io.EOF
+				}))
+			}
+			readers = append(readers, bytes.NewReader(helps.WrapConnectEnvelopeWithFlag(helps.ConnectFlagEndStream, []byte(`{}`))))
+
+			original := []byte(`{"model":"devin/swe-2","stream":true,"messages":[{"role":"user","content":"hi"}]}`)
+			if format == sdktranslator.FormatOpenAIResponse {
+				original = []byte(`{"model":"devin/swe-2","stream":true,"input":"hi"}`)
+			}
+			opts := cliproxyexecutor.Options{SourceFormat: format, OriginalRequest: original}
+			req := cliproxyexecutor.Request{
+				Model:   "devin/swe-2",
+				Payload: sdktranslator.TranslateRequest(format, sdktranslator.FormatInteractions, "devin/swe-2", original, true),
+			}
+			e := &DevinExecutor{}
+			e.streamDevinFrames(context.Background(), io.MultiReader(readers...), req, opts, "swe-2-high", format, nil, out)
+			drain()
+			if checkpoints != len(stages) {
+				t.Fatalf("reached %d checkpoints, want %d", checkpoints, len(stages))
+			}
+			if !slices.Equal(content, []string{"甲", "乙"}) {
+				t.Errorf("content deltas after EOS = %q, want [甲 乙] without loss or duplication", content)
+			}
+		})
+	}
+}
+
+func devinContentTestFrame(field protowire.Number, text string) []byte {
+	frame := protowire.AppendTag(nil, field, protowire.BytesType)
+	return helps.WrapConnectEnvelope(protowire.AppendString(frame, text))
+}
+
+func devinContentTestEvents(out <-chan cliproxyexecutor.StreamChunk) ([]gjson.Result, []error) {
+	var events []gjson.Result
+	var errs []error
+	for len(out) > 0 {
+		chunk := <-out
+		if chunk.Err != nil {
+			errs = append(errs, chunk.Err)
+		}
+		for _, line := range strings.Split(string(chunk.Payload), "\n") {
+			data := strings.TrimSpace(strings.TrimPrefix(line, "data: "))
+			if gjson.Valid(data) {
+				events = append(events, gjson.Parse(data))
+			}
+		}
+	}
+	return events, errs
+}
+
+func TestDevinStreamContentLateSignatures(t *testing.T) {
+	payload := make([]byte, 1+8+16+16+32)
+	payload[0] = 0x80
+	for i := 9; i < len(payload); i++ {
+		payload[i] = byte(i)
+	}
+	signature := base64.URLEncoding.EncodeToString(payload)
+	for _, format := range []sdktranslator.Format{sdktranslator.FormatOpenAI, sdktranslator.FormatOpenAIResponse} {
+		for _, split := range []bool{false, true} {
+			for _, ending := range []string{"eos", "trailer_error", "truncated", "read_error"} {
+				name := string(format) + "/late/" + ending
+				if split {
+					name = string(format) + "/split/" + ending
+				}
+				t.Run(name, func(t *testing.T) {
+					out := make(chan cliproxyexecutor.StreamChunk, 64)
+					var prefix bytes.Buffer
+					prefix.Write(devinContentTestFrame(9, "planning"))
+					tailSignature := signature
+					if split {
+						prefix.Write(devinContentTestFrame(10, signature[:20]))
+						tailSignature = signature[20:]
+					}
+					prefix.Write(devinContentTestFrame(3, "甲"))
+					var events []gjson.Result
+					checkpointReached := false
+					checkpoint := devinContentCheckpointReader(func(_ []byte) (int, error) {
+						checkpointReached = true
+						var errs []error
+						events, errs = devinContentTestEvents(out)
+						if len(errs) > 0 {
+							t.Fatalf("unexpected pre-signature errors: %v", errs)
+						}
+						var text strings.Builder
+						for _, event := range events {
+							if format == sdktranslator.FormatOpenAI {
+								text.WriteString(event.Get("choices.0.delta.content").String())
+							} else {
+								if event.Get("type").String() == "response.output_text.delta" {
+									text.WriteString(event.Get("delta").String())
+								}
+								if event.Get("type").String() == "response.output_item.done" && event.Get("item.type").String() == "reasoning" {
+									t.Error("reasoning item finalized before its late signature")
+								}
+							}
+						}
+						if text.String() != "甲" {
+							t.Errorf("content before late signature and termination = %q, want 甲", text.String())
+						}
+						return 0, io.EOF
+					})
+					var suffix bytes.Buffer
+					suffix.Write(devinContentTestFrame(10, tailSignature))
+					switch ending {
+					case "eos":
+						suffix.Write(helps.WrapConnectEnvelopeWithFlag(helps.ConnectFlagEndStream, []byte(`{}`)))
+					case "trailer_error":
+						suffix.Write(helps.WrapConnectEnvelopeWithFlag(helps.ConnectFlagEndStream, []byte(`{"error":{"code":"internal","message":"upstream failed"}}`)))
+					case "read_error":
+						suffix.Write([]byte{0, 0}) // Incomplete frame header causes io.ErrUnexpectedEOF.
+					}
+					e := &DevinExecutor{}
+					e.streamDevinFrames(context.Background(), io.MultiReader(&prefix, checkpoint, &suffix), cliproxyexecutor.Request{Model: "devin/swe-2"}, cliproxyexecutor.Options{SourceFormat: format}, "swe-2-high", format, nil, out)
+					remaining, errs := devinContentTestEvents(out)
+					events = append(events, remaining...)
+					if !checkpointReached {
+						t.Fatal("pre-signature checkpoint not reached")
+					}
+					wantError := ending != "eos"
+					if (len(errs) == 1) != wantError || len(errs) > 1 {
+						t.Errorf("stream errors = %v, want exactly one error: %v", errs, wantError)
+					}
+					var reasoningDone, completedReasoning gjson.Result
+					doneCount, messageDoneCount, completedCount, failedCount := 0, 0, 0, 0
+					var text strings.Builder
+					for _, event := range events {
+						if format == sdktranslator.FormatOpenAI {
+							text.WriteString(event.Get("choices.0.delta.content").String())
+							if event.Get("error").Exists() {
+								failedCount++
+							}
+							continue
+						}
+						switch event.Get("type").String() {
+						case "response.output_text.delta":
+							text.WriteString(event.Get("delta").String())
+						case "response.output_item.done":
+							if event.Get("item.type").String() == "message" {
+								messageDoneCount++
+							}
+							if event.Get("item.type").String() == "reasoning" {
+								reasoningDone = event.Get("item")
+								doneCount++
+							}
+						case "response.completed":
+							completedCount++
+							completedReasoning = event.Get("response.output.0")
+						case "response.failed":
+							failedCount++
+						}
+					}
+					if text.String() != "甲" {
+						t.Errorf("final content = %q, want 甲 without duplication", text.String())
+					}
+					if (failedCount == 1) != wantError || failedCount > 1 {
+						t.Errorf("failure event count = %d, want failure: %v", failedCount, wantError)
+					}
+					if format == sdktranslator.FormatOpenAIResponse {
+						if doneCount != 1 || reasoningDone.Get("encrypted_content").String() != signature {
+							t.Errorf("reasoning done count = %d, item = %s; want full signature %q", doneCount, reasoningDone.Raw, signature)
+						}
+						if messageDoneCount != 1 {
+							t.Errorf("message done count = %d, want 1", messageDoneCount)
+						}
+						if wantError {
+							if events[len(events)-1].Get("type").String() != "response.failed" {
+								t.Error("failure must terminate the stream after closing open items")
+							}
+							if completedCount != 0 {
+								t.Error("response.completed emitted after upstream failure")
+							}
+						} else if completedCount != 1 || completedReasoning.Raw != reasoningDone.Raw {
+							t.Errorf("completed reasoning = %s, want same item as done = %s", completedReasoning.Raw, reasoningDone.Raw)
+						}
+					}
+				})
+			}
+		}
+	}
+}
+
+func TestDevinStreamContentDoesNotOvertakeQueuedTool(t *testing.T) {
+	for _, format := range []sdktranslator.Format{sdktranslator.FormatOpenAI, sdktranslator.FormatOpenAIResponse} {
+		t.Run(string(format), func(t *testing.T) {
+			var frames bytes.Buffer
+			frames.Write(devinContentTestFrame(9, "planning"))
+			var tool []byte
+			for i, value := range []string{"call_1", "bash", `{"cmd":"ls"}`} {
+				tool = protowire.AppendTag(tool, protowire.Number(i+1), protowire.BytesType)
+				tool = protowire.AppendString(tool, value)
+			}
+			frames.Write(devinContentTestFrame(6, string(tool)))
+			frames.Write(devinContentTestFrame(3, "甲"))
+			out := make(chan cliproxyexecutor.StreamChunk, 64)
+			checkpointReached := false
+			checkpoint := devinContentCheckpointReader(func(_ []byte) (int, error) {
+				checkpointReached = true
+				events, errs := devinContentTestEvents(out)
+				if len(errs) > 0 {
+					t.Fatalf("unexpected errors: %v", errs)
+				}
+				for _, event := range events {
+					if event.Get("choices.0.delta.content").String() != "" || event.Get("choices.0.delta.tool_calls").Exists() || event.Get("type").String() == "response.output_text.delta" || event.Get("item.type").String() == "function_call" {
+						t.Errorf("queued tool or following text emitted before thinking signature: %s", event.Raw)
+					}
+				}
+				return 0, io.EOF
+			})
+			var tail bytes.Buffer
+			tail.Write(devinContentTestFrame(10, "CAQS-late-tool-signature"))
+			tail.Write(helps.WrapConnectEnvelopeWithFlag(helps.ConnectFlagEndStream, []byte(`{}`)))
+			e := &DevinExecutor{}
+			e.streamDevinFrames(context.Background(), io.MultiReader(&frames, checkpoint, &tail), cliproxyexecutor.Request{Model: "devin/swe-2"}, cliproxyexecutor.Options{SourceFormat: format}, "swe-2-high", format, nil, out)
+			events, errs := devinContentTestEvents(out)
+			if !checkpointReached || len(errs) > 0 {
+				t.Fatalf("checkpoint = %v, errors = %v", checkpointReached, errs)
+			}
+			toolSeen, textSeen := false, false
+			for _, event := range events {
+				if event.Get("choices.0.delta.tool_calls.0.id").String() == "call_1" || (event.Get("type").String() == "response.output_item.done" && event.Get("item.call_id").String() == "call_1") {
+					toolSeen = true
+				}
+				if event.Get("choices.0.delta.content").String() == "甲" || (event.Get("type").String() == "response.output_text.delta" && event.Get("delta").String() == "甲") {
+					textSeen = true
+					if !toolSeen {
+						t.Error("content overtook queued tool")
+					}
+				}
+			}
+			if !toolSeen || !textSeen {
+				t.Errorf("tool seen = %v, text seen = %v; want both", toolSeen, textSeen)
+			}
+		})
+	}
+}